Mount Prospect, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

855
FXUS63 KLOT 281105
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
605 AM CDT Sat Mar 28 2026

.KEY MESSAGES...

- One more seasonably cool day before temperatures start
  warming Sunday into early next week.

- Elevated fire weather conditions today and possibly again on Sunday.

- Stormy weather pattern returns towards the middle of next
  week.

&&

.DISCUSSION...
Issued at 315 AM CDT Sat Mar 28 2026

Through Sunday Night:

A surface high continues to drift overhead early this morning
which is setting up a clear but chilly start to our Saturday.
Temperatures will rebound this afternoon under mostly clear
skies and increasing warm advection, though highs look to only
top out around 50 degrees at best which is around average for
late March. That said, dew points today are expected to remain
in the mid to upper teens (lower teens in northwest IL) which
will generate afternoon humidities around 25-30%. Couple these
conditions with the breezy southwest winds gusting around 20-25
mph and conditions look favorable for an elevated risk for grass
and brush fire spread. However, with fuel moistures on the more
marginal side (around 10-15%) the set up today looks a bit too
marginal to warrant the issuance of a Special Weather Statement
at this time. Nevertheless, anyone planning to be burning today
should use caution especially during the period of strongest
winds this afternoon.

While the strongest winds will diminish this evening, the
continued warm advection looks to keep the atmosphere at least
loosely mixed which may allow occasional 15-20 mph gusts to
linger. Though, temperatures will be more mild tonight as some
increasing cloud cover and the warm advection hold readings in
the upper 30s to around 40.

Sunday will feature similar conditions to today but with
notably warmer temperatures (highs in the low to mid-60s). Winds
will once again become breezy during the afternoon with gusts
around 20-30 mph, however, these winds will begin to advect in
higher dew points throughout the day. Therefore, the afternoon
humidities look to be a bit better (in the 25-35% range) which
should limit the fire weather concerns. Though, if dew points
are slower to rise than forecast then another period of elevated
fire conditions could materialize Sunday afternoon. Otherwise,
expect another mild night Sunday night with lows in the upper
40s and lower 50s.


Monday through Friday Night:

The extended period continues to look active as a deepening
shortwave trough is forecast to begin moving onshore across the
Pacific Northwest on Sunday followed by broader troughing that
will drift eastward during the later part of next week. The
aforementioned shortwave is still expected to traverse across
the northern Plains and Upper Midwest Monday into Tuesday with a
weaker secondary wave expected to eject out of the southern
Plains and into the Great Lakes Monday night. As the southern
wave approaches, a warm front is expected to move through
northern IL and northwest IN on Monday. While the warm front
will gradually moisten the lower levels of the atmosphere,
forecast soundings do show a notable mid-level dry layer that
looks to keep the atmosphere capped as the front moves through.
Therefore, dry conditions should prevail through the daytime
hours on Monday. Temperatures on the other hand will be on the
rise Monday with highs forecast to be back into the lower to
mid-70s for most. However, as is typical with warm fronts this
time of year the cooler waters of Lake Michigan may limit its
northward progress and result in onshore winds and notably
cooler temperatures along the IL shore.

Heading into Monday night, the mid-level dry layer is progged
to gradually wane as a slug of Gulf moisture is advected into
the area. This diminishing of the cap in combination with the
subtle forcing from the weak shortwave and warm advection may
allow for a few scattered showers and/or thunderstorms to
develop. The latest 00z guidance suite seems to still favor a
drier forecast, however, likely due to the cap being too strong
to fully erode especially without the aid of diurnal heating.
Based on this, I suspect that the chances for showers/storms
Monday night is more on the order of 20-30% as opposed to the
40-50% offered by the NBM. Since there is still some uncertainty
as to the cap`s strength opted not to make any adjustment to
the NBM POPs just yet.

A better coverage of showers and thunderstorms is expected to
occur on Tuesday as the northern stream shortwave and its
associated surface low push a cold front through northern IL and
northwest IN. The environment ahead of the front continues to
look unstable with steep mid-level lapse rates and over a 1000
J/kg of CAPE noted in forecast soundings which in combination
with the 40-45 kts of deep layer shear present may support a few
strong to possibly severe storms as well. Overall, guidance has
remained in good agreement for Tuesday but there continues to
be some differences as to the exact timing the cold front will
push through. If the later timing (which seems to be favored in
the 00z guidance suite) persists, then the northern extent of
any stronger storms could be limited. Additionally, the later
solutions would also mean that more locations see highs in the
mid to upper 70s Tuesday afternoon but if the faster solutions
verify than some could see notably cooler conditions. For now
our official forecast will lean towards these later solutions
with the better coverage of showers/storms Tuesday afternoon and
evening and warmer temperatures areawide. Though, we will
continue to keep a close eye on this period and adjust as trends
support.

Guidance has started to trend into better agreement that the
cold front will push through the area and stall closer to the
Ohio and Tennessee River Valleys Tuesday night into Wednesday.
Therefore, it appears that Wednesday and Thursday may be
actually dry as a surface high pivots over the Great Lakes. As a
result the latest NBM/WPC POPs for Wednesday and Thursday have
come down, but still maintain a 20-30% chance due to some
guidance members being slower and further north with the front.
Beyond Thursday forecast confidence continues to be low as
guidance varies on the timing and intensity of trailing
shortwaves that will be traversing the broader Pacific
troughing. So while our official forecast does have higher
precipitation chances returning as early as Thursday night,
there is a signal that precipitation could hold off until
Saturday when a more notable system moves through the region.
Regardless, temperatures behind Tuesday`s cold front will be
much cooler with highs in the 40s and 50s to close out the week.

Yack

&&

.AVIATION /12Z TAFS THROUGH 18Z SUNDAY/...
Issued at 605 AM CDT Sat Mar 28 2026

There are no significant aviation weather concerns anticipated
through the period.

A rather stout surface high will slide across the region
early this morning. This will foster a period of light and
variable winds for a couple hours this morning. However,
directions will quickly settle into a south-southwesterly
direction by mid to late morning following the eastward
departure of the surface high. Later in the day, as diurnal
mixing maximizes, expect some gusts up to 20-25 kt to develop
for a period before abating this evening.

KJB

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...Small Craft Advisory until 10 AM CDT this morning for the IN
     nearshore waters.

&&

$$

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